Lamp.



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Patented July 30., 1918.

WILLIAM J. BOHAN, OF ST. PAUL, MINNESOTA.

LAMP.

Specification 0! Letters Patent.

Patented July 30, 191 8.

Application filed October 5, 1817. Serial No. 194,926.

To all whom it may concern:

Be it known that I, WInmAM J. BOHAN, a citizen of the United States, andresident of St. Paul, county of Ramsey, and State of Minnesota, haveinvented certain new and useful. Improvements in Lamps, of which thefollowing is a specification and which are illustrated in theaccompanying drawings, forminga part thereof.

The invention relates to projecting lamps, such as headlights; itsobject being to rovidc improved means for focusing tlie lllllminant withreference to the projecting lens.

An embodiment of the invention is here inafter described, and isillustrated in the accompanying drawings, in which-- Figure 1 is alongitudinal central sectional view of the lamp;

Fig. 2 is an elevation of the rear end thereof; and

Fig. 3 is a detailcentral longitudinal section showing amodified form ofconstruction.

The lamp comprises a shell 10 for inclosing a projecting reflector 11,the shell having a tubular stem 12 which is preferably externallythreaded, and the reflector is rovidcd with a central aperture 13,throng which the base 14 of an incandescent bulb 15 pro jects. A cap 16is applied to the rear end of the stem 12, and has an annular flange 17engaging it and being axially adjustable thereon, preferably, as shown,being in threaded engagement therewith. The cap 16 is also provided witha central tubular stem 18, projecting into the aperture of the stem 12and being of substantially less diameter than the bore of the latterstem.

The base of the incandescent bulb 1a is rounded, as shown at 19, takingthe form of a section of a sphere, and is seated. against the end of thestem 18, which is of corre sponding curvature. A threaded .rod 20 fixedcentrally. to the curved portion 19 oi the base 14', extends through thestem 18 and has applied to its outer end a nut 21, the face of which isconcave and concentric with the end of the bulb base and seats against acorresponding outer face 22 of the ca 16. The bore of the stem 18 issuificiently large to ermit lateral movement of the rod 20. he bulb 15is adjusted axially by advancmg or retracting the cap 16 on the stem 12.This is accomplished in the construction shown by a turniigg movement.Where both axial and lateral ifting becomes necessary,

in dotted lines, Fig. 1, to move the bulb through an arc, and this isreadily done by the shifting of the nut 21.

When properly focused the nut 21 is screwed down firmly and is lockedsecurely against movement by any suitable means, such as the swingingarm pivotally, attached to the cap 16, and with which coiitidr ates awing nut 24, running on the threaded stem of a link 25 also pivoted tothe cap, the arm 23 being slotted to receive the link.

In the construction shown in Fig. 3, the rounded base 14 of the bulb isseated against the inner concave end of a tubular member 26, which isprovided at its outer end with 21 head 27 forming a partition across theinterior of the cap 28 with which it is in threaded engagement, such capbeing screwed upon the flange ofa cap 28, which threaded portion alsoruns upon the threads of the stem 12. The rod 29 projecting backwardlyfrom the base 14 extends through the member 26 and through an enlargedaperture 30 in the cap 28, its outer end being threaded for theengagement of a nut 31, the inner face of which is concave andconcentric with the curved end of the bulb base, the outer face of thecap 28 being correspondingly curved. A spring 32, coiled. about the rod29, reacts between the nut 31 and an abutment block 34 slidably mountedupon the rod and bearing against the outer curved face of the head 27 ofthe member 26. Preferably a lead washer 35 is interposed between theabutment 34 and the head 27.

In assembling the parts the spring 32,

abutment 34, and washer 35 are placed within the cap 28. The member 26is then screwed into the cap and the assembled parts are fitted upon.the rod 29, the cap 28 being screwed up upon the stem 12, whereupon thenut 31 is applied. In effecting the axial adjustment of the bulb the cap28 is turned on the stem 12, and with it the member 26, shifting thebulb as may be required.

The leading-in wires 36 may enter the casing and bulb at any convenientplace, preferably through the rod 20 or 29,.which is made tubular fortheir accommodation. The adjusting movements are the same in theconstruction shown in Fig. 3 in that of Fig. 1.

Various changes of detail may be made without departing from the scopeof the in vention. For example, while the part 27 is shown as threadedinto the cap 28, it may, of course, be made integral therewith.

I claim as my invention 1. In a lamp, in combination, a shell having athreaded tubular stem, at reflector housed within the shell, anincandescent bulb located Within the reflector and having a baseextending into the stem of the shell, the rearward end of the basehaving the form of a section of a sphere, a cap in threaded engagementwith the stem of the shell and having an inwardly projecting tubularstem a ainst the end of which the base of the bul is seated, a rodprojecting backwardly from the bulb base, and a nut threaded upon theend of the rod and en aging the rear face of the cap, the face 0 the nutand the surface of the cap against which it bears being concentric withthe rear end of the bulb base.

2. In a lamp, in combination, a shell having a tubular stem, anincandescent bulb within the shell, the base of the bulb projecting intothe stem and being rounded at its rearward end to the section of asphere, a cap longitudinally adjustable on the stem and having aninternal seat for the bulb base complementary in form to the rear endthereof, a threaded rod projecting back wardly from the bulb basethrough the ca and being capable of lateral movement wit referencethereto, a nut on the outer end of the rod and adapted to bear upon therearward face of the cap, a transverse apertured partition in the cap, ablock slidable on the rod and engageable with the partition, and aspring encircling the rod and reacting between the nut and the block,the rearward face of the cap and the surface of the partition beingconcentric with the rear end of the bulb base.

In a lamp, in combination, a tubular support, a cap threaded upon thesupport and having concentric inner and outer curved seats, a lamp basecomplementary to and engaging the inner seat and having a stem extendinglaterally through both seats, a member fitting upon the stem and beingcomplementar to and engaging the outer seat, and means for binding suchmember to said seat.

W ILLIAM J. BOHAN.

It is heraby cortifiadjhat in Letters Patent No. 1,273,995; granted July30, 1918, upon the application of William J. Bohan, of St. Paul,Minnesota, for an improvement in Lamps," an error appears in the printedspecification requiring correction as follows: Page 1, lines 81-82,strike out, the words the flange 0; a cap 28, which thriaaded portionnlsuruns Upon the threads of"; and that the said LBHOIS Patent. shouliibe read with this correction therein that the same may conform to themoon of the cae in the Patent Office.

Signed and sealed this 27th day of August, A. D., 1918.

[sun] F. w. u. CLAY,

Acting Commisiiimwr of Patents.

